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Emergency Light/Charger from Fire & Water

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DIY a really simple Thermoelectric Emergency Generator from very few parts.
Optimized for powering with tealights/candles.


With inspiration from my previous projects:
http://www.instructables.com/id/Thermoelectric-Fan-Driven-by-a-Candle/
and
http://www.instructables.com/id/Battery-Charger-Powered-by-Fire/

This was made as an experiment to test efficiency when using water as cooling component in a thermoelectric system. The result was very interesting and as it was really easy to make I thought I could share this too.


Background:
It converts heat energy (from candles) into electricity. Main usage is to power LED lights to act as an emergency product. It could also be scaled up and used in homes where electricity is not very given. It could also be used as a battery charger or power other electronic devices. I´m well aware of the commercial product tPOD1 which I think is a great idea but I´m more interesting in a DIY solution for everyone.

Concept:
I´m using a thermoelectic module, also called peltier element, TEC or TEG. You have one hot side and one cold. The temperature difference in the module will start producing electricity. The physical concept when you use it as a generator it's called the Seebeck effect. Thermoelectic modules are mainly used for the opposite effect, the Peltier effect. Then you apply a electric load and it will force a heat transfer from one side to the other. Often used in smaller refrigerators and coolers. Read more about i here:
http://en.wikipedia.org/wiki/Thermoelectric_effect

Solution:
First I used a cheap TEC-module (8€) but it was unfortunately destroyed due to high temperatures. It was specified to handle 200ºC max temperature but somehow I got higher temp than I measured. I ran it without load, that might be the cause. I now use a 40x40mm TEG-module that produce 5.9W (4.2V/1.4A) at 180ºC difference. It has a maximum operating temp of 350ºC (180ºC cold side). It was the same module I used in my other charging project. It´s quite expensive though, about 50€. TEGs are a bit hard to come by but I think there are cheaper ones available.

To transport away all heat and cool it with air you usually need a large heat sink, or a small heat sink with a motor and fan. In this project I use water instead. That make the contruction really compact and the temperature on the "cold" side will never exceed 100ºC. Water will eventually boil but it´s easy to refill, as long as you have water.

To power LEDs you need higher voltage than the module itself produce. In my previous project I built an adjustable regulated voltage Step-up. That could be used (and is better) but I choose to use a $1 step-up from Ebay.

The best choice of heat source is 3x tealights. That produce about 0.2W electric power.

Features:
  • 90g (without LED)
  • WxH=85x78mm
  • Built in voltage step-up
  • Support for 3x tealights

Applications:
Mainy constructed to power LEDs but can be used for other things as well:
  • Battery/smartphone charger
  • External fan (cooling effect, fire booster, etc.)
  • Electronics
  • Charge super capacitor and power high intensity SOS signals
Could also be heated with lots of stuff:
  • Candles
  • Spirit burner/stove
  • Gas burner/stove
  • Wood stove
  • Camp fire
  • Barbecue
  • Hot water

Donations:
High effect thermoelectric modules are expensive. If you would like to see more of those experiments in the future, please consider a small donation.
Bitcoin address: 1BouwowuprgQrtUYgyzYnNvHyRYbLceqHg
 
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hay mate where did you get

Built in voltage step-up

from ebay ?

Joohansson (author)  dripperjgmail.com1 month ago
Search for "emergency aa battery portable dc charger"

thanks mate

Kais Kermani9 months ago
Just Awesome !!
WastelandMan9 months ago
Very well done! Thank you do much for this guide. I can't wait to try this!
132810 months ago
Please mail me detail layout of TEG or TEC module.

Is it possible to make peltier module at home.

Thanks a lot
phillam11 months ago
I love these projects. Great work. I have often thought about lining a chimney flue with peltier modules. I live off grid and during winter solar is down especially with cold batteries. We pretty much run a fire 24/7 and an external flue seems perfect to line with these modules, ie sub zero outside very hot inside. Granted you need maybe 30 of them but comparing the costs and wattage output to a solar panel it really isn't that bad and they run at night! These projects are very inspiring. Thanks!!!
ejb11 months ago
Great instructable!!

Really awesome to see your progression through the various peltier projects you have made.

Voted :-)
agis6811 months ago
your project reminded me the peltier projects i did some years ago but then were very expensive and not so many size varietes. Very good instructable!!!
AuralVirus11 months ago
These are they type of projects I love to see at instructables.
I8mAll11 months ago
I too saw a Russian generator but this one was part of the flue immediately above a pot-belly stove. It was powerful enough to drive a radio transmitter. VW has experimented with bimetallic exhausts to harvest waste energy. Your idea of using a step up converter is very elegant.
XenonJohn11 months ago
Surfing the web years ago on this concept I found the Russians had a thing like a poker. You put one end in the fire and wires came out of the other end to power a radio. It used dissimilar metals rather than peltier unit. They also had a oil lamp with metal fins sticking out of the sides that did the same thing.

I like the idea of a camping stove that charges up your gadgets at the same time. As you say, just make sure the boiling water never actually boils dry.

John
tutdude9811 months ago
so with 30ºC you will get more power than with 75ºC?
Joohansson (author)  tutdude9811 months ago
That is temperature of the water. Cooler water means higher temperature difference compared to the hot side. The higher power at 75ºC is a consequence of the module's higher efficiency at higher temperatures I think. But the temperature difference if very similar across the whole interval. It does not matter that much if you fill it with snow or boiling water. The heat transfer through the module is like a resistance and it require more heat energy to increase the temperature difference as it is constantly cooled on the other side.
RosyRivet11 months ago
Can TEC elements be salvaged from junk refrigerators?
Joohansson (author)  RosyRivet11 months ago
Not large refrigerators with compressor but smaller portable ones usually have peltier elements inside. The problem with those is that they normally are not made for high temperatures. You may damage them if not careful.
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